Elevator mechanism for reducing web tension and controlling elevator descent

ABSTRACT

An improved elevator mechanism for reducing the tension of the web to a tolerable value, and for controlling the rapid descent of the movable carriage of the elevator mechanism. A series of film supporting spools is provided at the top and bottom of the elevator mechanism to form a multiplicity of film storage loops. The improved elevator mechanism comprises providing a deflectable top spool which is movable by web tension into engagement with an overdriven drive roller.

United States Patent [191 Nielsen ELEVATOR MECHANISM FOR REDUCING WEB TENSION AND CONTROLLING ELEVATOR DESCENT Inventor: Leroy C. Nielsen, Spencerport, N.Y.

Assignee: Eastman Kodak Company,

' Rochester,

Jan. 5, 1973 Filed:

Appl. No.:

US. Cl. 242/55.01 Int. Cl B65h 75/00 Field of Search 242/55.01; 226/118, 119

References Cited UNITED STATES PATENTS 4/1968 Feasey ..242/55.0l 3/1970 Thomas ..242/55.0l

[111 3,827,646 Aug. 6,1974

10/1972 Treise 242/55.0l 3,743,195

7/1973 Bagdasarian 242/55.0l

Primary Examiner-John W. l-luckert Assistant Examiner-Edward J. McCarthy Attorney, Agent, or Firm-S. W. Gremban [57] ABSTRACT An improved elevator mechanism for reducing the tension of the web to a tolerable value, and for controlling the rapid descent of the movable carriage of the elevator mechanism. A series of film supporting spools is provided at the top and bottom of the elevator mechanism to form a multiplicity of film storage loops. The improved elevator mechanism comprises providing a deflectable top spool which is movable by web tension into engagement with an overdriven driv'e roller.

6 Claims, 2 Drawing Figures ELEVATOR MECHANISM FOR REDUCING WEB TENSION AND CONTROLLING ELEVATOR DESCENT BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to elevator mechanisms, and more specifically to an improved elevator mechanism for reducing web tension to a tolerable value, and for controlling the rate of descent of the movable carriage of the elevator mechanism.

2. Description of the Prior Art Elevator mechanisms for storing a web at either end of a processing device to permit continuous transport of the web through the device during momentary stoppage of web transport into or out of the device are well known in the art. Such elevator mechanisms are particularly useful in the photographic film processing art. In such elevator mechanisms, one or more upper stationary shafts are provided containing a plurality of axially spaced apart, film supporting spools. The lower portion of the elevator mechanism comprises a reciprocally movable carriage having substantially an equivalent number of shafts and spools. The film is threaded through the elevator mechanism around the film supporting spools to form a multiplicity of film storage loops in the elevator mechanism. If the elevator mechanism is located at the feed end of the processing device, the film feed is controlled to rapidly fill the elevator mechanism for storing a maximum length of film. In such filled condition the movable carriage is substantially at the bottom of its range of travel, and actuates a switch terminating further film feed into the elevator mechanism. The procesing device continues to operate pulling the film from the elevator mechanism causing the carriage to rise. Normally, any splcing operation or the like that is performed at the feed end is completed and the film feed commenced before the carriage arrives at its uppermost position. When the film feed is commenced, the film is fed in rapidly to refill the elevator mechanism, causing the carriage to descend rapidly to its filled position. To prevent the elevator carriage from crashing at the bottom of the elevator mechanism, a water cushion tube is provided interposed between the carriage and elevator bottom to slow down the carriage in much the same way that a shock absorber dampens movement. The film tension which has a tendency to increase, particularly where a large number of spools are involved, is reduced by rotating the top spool bearing shaft at a rate of about four times the speed at which the spool shafts are normally driven. Although driving the upper shafts at a higher rate of speed and providing a water cushion tube reduces the film tension in the elevator mechanism and controls the descent of the elevator carriage respectively, such system suffers from lack of economy and efficiency of operation.

SUMMARY OF THE INVENTION In accordance with a preferred embodiment of the invention, an improved elevator mechanism is disclosed for reducing the web or film tension in the elevator mechanism to a tolerable value, and for controlling the rapid descent of the movable carriage of the elevator mechanism. The improved elevator mechanism comprises a first shaft rotatably supporting a plurality of axially spaced apart, web supporting spools including a deflecting spool capable of limited radial deflection under the influence of increased film tension, and a second shaft parallel to the first shaft for rotatably supporting a plurality of film supporting spools. The film is trained over the film supporting spools on the first and second shafts to form a multiplicity of film storage loops. A reciprocally movable carriage means is provided for supporting the second shaft for upward movement when film is withdrawn from the elevator, or downward movement when film is stored therein. A drive roller is mounted adjacent but spaced from the deflecting spool and is driven at a substantially higher speed than the normal speed of the deflecting spool. Accordingly, any increase in the film tension in the elevator mechanism above a predetermined value for any reason causes the deflecting spool flanges to deflect into engagement with the drive roller which overdrives the deflecting spool, causing a reduction in film tension to a tolerable value. Should the elevator carriage descend rapidly, causing the spools to rotate faster than the drive roller, the increased film tension again moves the deflecting spool into engagement with the slower rotating drive roller which now acts as a brake preventing the deflecting spool from rotating faster than the drive roller, and hence causing the elevator carriage to descend at a tolerable rate of speed. Since the film speed in the elevator going up or down is normally the least variable at the middle of a plurality of upper spools, the middle spool is normally arranged to be the deflecting spool. Naturally, one or more of the other upper spools may also be arranged to be deflecting spools movable into engagement with a corresponding drive spool. The primary advantage of the improved elevator mechanism of this invention is that it is more efficient and economical than prior known mechanisms.

It is, accordingly, one of the objects of the present invention to provide an improved elevator mechanism that is of simple design and construction, thoroughly reliable and efficient in operation, and economical to manufacture.

The invention and objects and advantages will become more apparent from the detailed description of the preferred embodiment presented below.

BRIEF DESCRIPTION OF THE DRAWINGS In the detailed description of the preferred embodiment of the invention presented below, reference is made to the accompanying drawing, in which:

FIG. 1 is a front elevational view with a portion thereof broken away, illustrating a preferred embodiment of the elevator mechanism of this invention; and

FIG. 2 is a partially elevational and section view taken substantially along line 2-2 of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Because elevator mechanisms are well known, the present description will be directed in particular to elements forming part of, or cooperating more directly with, apparatus in accordance with the present invention. Film elevator elements not specifically shown or described herein should be understood to be selectable from those known in the art.

With reference to the drawing, a preferred embodiment of an improved web or film elevator mechanism of this invention is illustrated comprising spaced apart U-shaped channel members 4 for supporting a stationary upper shaft 6 whose ends are secured to frame members 4 by any suitable means, such as nuts 8. A plurality of film supporting spools 10 of known type are mounted on shaft 6, most of which are mounted on bearings, not shown, interposed between shaft 6 and spool 10, and at least one of which is a deflecting spool 12 mounted for rotation on shaft 6. The deflecting spool 12 is preferably a spring core spool of the type disclosed in US. Pat. No. 3,498,556. The spring core spool 12 has a substantially rigid central hub 14 arranged to rotate freely on shaft 6 coaxial with the axis thereof, and a film support rim l6 coaxial with the shaft and integrally connected to hub 14 by one or more flexible spiral members 18 which permit rim 16 to be deflected radially with respect to the axis of hub 14. A drive shaft 20 parallel to shaft 6 is rotatably journaled in bearings 22 supported by frame members 4, and is driven by any suitable means, not shown, for rotating a polyurethane-covered drive roller 24 of any suitable type secured thereto. The drive roller 24, preferably provided with a high friction driving surface, is axially positioned in register with deflecting spool 12 and spaced apart therefrom a small distance. When the film tension in the elevator mechanism increases to a predetermined value, the rim 16 of the deflecting spool is deflected, causing flanges 26 secured by any suitable means to rim 16, and made of brass or steel for better wear purposes, to be moved into contact with drive roller 24 as shown dotted in FIGS. 1 and 2.

A reciprocally movable carriage means is provided at the lower end of the elevator mechanism comprising one or more parallel shafts 28 for supporting a plurality of film supporting spools 30, of known type, for rotation thereon. In FIGS. 1 and 2, only one lower shaft 28 is shown extending through slot 33 in channel 4 and secured by nuts to side plates 27. The side plates 27 are secured together by a rod 29, and are provided with rollers 32 engageable with surfaces 34 of channel 4 for guiding the carriage for reciprocal vertical movement. Switch means, not shown, are normally provided at the lower end of the elevator mechanism, and responsive to the carriage for stopping the film feed. In such position, the elevator mechanism is filled and the maximum footage of film stored therein. Although only a single upper and a single lower shaft is shown in the drawing, it should be understood that normally such elevator mechanisms comprise a plurality of upper and lower shafts, the lower shafts all being supported by any suitable reciprocally movable carriage.

In the operation of this invention, a film 36 from any suitable film supply, not shown, is threaded around the upper and lower spools 10,30 respectively of the elevator mechanism to form a multiplicity of film loops. The film 36 is fed into any suitable processing device, not shown. If the film tension in the elevator mechanism should increase above a predetermined value for any reason, the flanges 26 of deflecting spool 12 are moved into engagement with drive roller 24 which drives spool 12 at a higher rate of speed than the normal speed of rotation of the spools 10,12. It has been found that driving spool 12 at a speed substantially percent higher than its normal speed of rotation satisfactorily reduces the film tension to a desired level. In those situations where the elevator carriage is descending rapidly, the increase in film tension also moves deflecting spool 12 into engagement with drive roller 24. However, since the speed of rotation of spools 10,12 during rapid descent of the elevator carriage are normally four or five times greater than the rotational speed of drive rollers 24, moving spool 12 into engagement with drive roller 24 has the effect of braking the speed of the spool 12, whereupon the speed of spool 12 and the remaining spools 10 is maintained substantially at the speed of the drive roller. Such action has the effect of reducing the rate of descent of the elevator carriage to a safe value. Although only one deflecting spool 12 is shown, any number of such spools and corresponding drive rollers 24 may be used. Since in such elevator mechanisms the film speed during elevator movement is the least variable at the middle film loop, for best operating results at least the middle spool along any upper shaft 6 is arranged to be a deflecting spool.

The invention has been described in detail with particular reference to a preferred embodiment thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove.

I claim:

1. In an improved elevator mechanism for storing and releasing a web at one end of a processing device to permit continuous transport of the web through the device during momentary stoppage of web transport at said one end of the processing device, said elevator mechanism having a web inlet end and a web outlet end, the combination comprising:

a first shaft rotatably supporting a plurality of first spaced apart web supporting spools including a deflecting spool capable of limited radial deflection under the influence of increased film tension;

a second shaft parallel to said first shaft for rotatably supporting a plurality of second spaced apart web supporting spools, said web being trained over said first and second web supporting spools in a multiplicity of loops and transported through said elevator mechanism for driving said first and second spools at a normal speed;

reciprocally movable carriage means for supporting said second shaft for upward movement to release a substantial length of web when web stoppage occurs at the inlet end of said elevator mechanism and downward movement to store a substantial length of web when web stoppage occurs at the outlet end of said elevator mechanism; and

a drive roller mounted adjacent but spaced from said deflecting spool and driven at a higher speed than said normal speed of said first spools;

said carriage adapted when rapidly descending to cause said deflecting spool to move into driving engagement with said drive roller due to the increased web tension whereby said deflecting spool is driven faster than said normal speed to reduce the web tension, said drive roller serving to brake the descent of the carriage by preventing the speed of said deflecting spool from substantially exceeding the speed of said drive roller.

2. The invention according to claim 1 wherein said deflecting spool is a spring core spool.

3. The invention according to claim 1 wherein said deflecting spool is provided with metal flanges for engaging said drive roller.

4. The invention according to claim 3 wherein said drive roller is provided with a polyurethane drive surface.

5. The invention according to claim 1 wherein said shafts, and said deflecting spool is a freely rotatable spring core spool.

6. The invention according to claim 5 wherein said deflecting spool is substantially axially centered befirst and second shafts are stationary, said first and sec- 5 tween the remainder of said first spools.

ond spools are freely rotatable on their respective 

1. In an improved elevator mechanism for storing and releasing a web at one end of a processing device to permit continuous transport of the web through the device during momentary stoppage of web transport at said one end of the processing device, said elevator mechanism having a web inlet end and a web outlet end, the combination comprising: a first shaft rotatably supporting a plurality of first spaced apart web supporting spools including a deflecting spool capable of limited radial deflection under the influence of increased film tension; a second shaft parallel to said first shaft for rotatably supporting a plurality of second spaced apart web supporting spools, said web being trained over said first and second web supporting spools in a multiplicity of loops and transported through said elevator mechanism for driving said first and second spools at a normal speed; reciprocally movable carriage means for supporting said second shaft for upward movement to release a substantial length of web when web stoppage occurs at the inlet end of said elevator mechanism and downward movement to store a substantial length of web when web stoppage occurs at the outlet end of said elevator mechanism; and a drive roller mounted adjacent but spaced from said deflecting spool and driven at a higher speed than said normal speed of said first spools; said carriage adapted when rapidly descending to cause said deflecting spool to move into driving engagement with said drive roller due to the increased web tension whereby said deflecting spool is driven faster than said normal speed to reduce the web tension, said drive roller serving to brake the descent of the carriage by preventing the speed of said deflecting spool from substantially exceeding the speed of said drive roller.
 2. The invention according to claim 1 wherein said deflecting spool is a spring core spool.
 3. The invention according to claim 1 wherein said deflecting spool is provided with metal flanges for engaging said drive roller.
 4. The invention according to claim 3 wherein said drive roller is provided with a polyurethane drive surface.
 5. The invention according to claim 1 wherein said first and second shafts are stationary, said first and second spools are freely rotatable on their respective shafts, and said deflecting spool is a freely rotatable spring core spool.
 6. The invention according to claim 5 wherein said deflecting spool is substantially axially centered between the remainder of said first spools. 